Income Taxes - Operating Loss Carryforwards (Details) - State [Member] $ in Millions	Dec. 31, 2016 USD ($)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 21
Tax Years 2022 - 2026 [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	1
Tax Years 2027 - 2031 [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 20